Anemometer.



A. OGiLVlE.

ANEMOMETER.

APPLICATION FILED JUNE 1. 1914.

Patented July 13, 1915;

3 SHEETS-SHEET1 f" m M A. OGILVIE.

ANEMOMETER.

KPPLICATION FILED JUNE 1. 1914.

Patented July 13, 1915.

3 SHEETSSHEET 2- Vil -lie A. OGILVIE.

Patented July 13, 1915.

3 SHEETS-SHEET 3- l ii hTdaZZ whom it mag came a:

and the *obj ect of thesaid inyent'ionis Be it known that I, ALndOcIiiIE, sub- "i'ec b lth n f Gfeat 'Biifai sfi si hs at Eastchurch,"Sheppey, infthe {countyof Kent, England, have i vent-ed emain newanduseful Improvements in Anemoineters, and of which the, following, is{a "specification; i I

" This, invention" relates V to aneihometrs,

able the pressure of fluid rece ved in a ,tiilie or through an aperture,v on "an approximately evenly dividedfscale, not

graduated in proportion with ft totherelatwe speedof trayelpt'the airimpinging on the entrance to the tube.

.ee' e pressure, but in graduations corresponding It is Well known thatthe prssureef air received by a'nozzle or 'tubef'th'el open end ofwhichfi's' directed against the fibw of air, increases as the square ofthe speed oft'ra'vel of thesa'i'd' air. If thereforeaii instrument bemade with an indicator moving ia m portion to the variationsof presure-and the dial be graduated to shoivthefvari'ation's of speed oftravel of the fair duet-o such variations of pressure, then as the ispeeds varyjthe extent of 'movement of 'thefindicator relatively to theextentof change in thespeed of the air, is much greatenfor changes. athigher speeds thanjfor similar changes at lower speeds. i "","I

Varying distances ofmovement of the indicating mechanism to'indicateregular changes of speed of the travelingaifirender suchindicating mechanism "eXtremely unsatisfactory in "use,'; especiallyquick readings on aeroplane flying machines.

a is therefore eminently "desirable iin' "instruments for indica'tingspeed of travel- 6f air or of a flying machine'through' airjfor'the dialto he graduated in: even divisions and for the hand or indicator to movea distance equal in proportion to the hangefof speed of the air ormachine. 4 V v I According to this invention; the tube which receivesthe'press'ur'e of the air,'co1nmunicates with indicating" or"'rec ording'me chanism, the latterbeing sodesigned'as to produce a movement of:the'indic'atoron the scale, approximately proportional to" the squareroot of'the pressure, and this value tioni in movement upon increase'ofpressure taking place, balances, or partly compensates for theaccelerated lncreaseinpressure in proportion as the speed of the airALEG osn'ivm, ;OF EASTGHURQH,I snnrrnnnnennnnz b mesfereei hisfre i a pment f "i la l mi a hra ,.Wh10h otters? g ater esifstance to movement pmitte d thro 'chamher 'of' whichftliediaphragm forms one the 'Wallswhilejthe xoppositef'side of the diaphragmis ect to atmosphericpresxpanded or ia hraamissmashed ule said tube-to ayesa otherconvenient=3= ntra cc to the" tube "is transsure, or topresgsureireceiyed in any prifice or eceiVe-pressure,orthrough which ffs'uctionj; takes place, in i accordance with th'e speed officwef, thefluid,an'd"conair traveling past the said entrancehsothe f pressure"infthe pressure chamber increases ;or decreases. At the lower speeds,the

pressurefvaries, toa comp aratiyely small eX- "tent, and fat the flo erpressure the dia- 3 phraginis correspondingly easy'in its iii'oyeinents,:but; asthe pressu're increases 'owing to, the greater "spe ds attained,the, diaphi-21am; becoming more extended, moves to a less extent n Tfeoperation oftheinstrument is leased -phragm.s 1cha'szfithat employed,assumes an approximately sph'eiical' form "when acted on by a uniformpre'ssure, and the deflection of the center ofthe "diaphragm is thenproportional tothe square rootjof the pressure acting. .This'mo'v'ementoffith'ecenter of thediaphiagm -"being proportional" tothe square rootof the-pressure, compensatesfor ;;the pressure received in "the'finstri'iment -increasing as" the square of the s eed of i thetraveling-flair {being 'ineasured, Thus an proportion to increases in a{1' :5

evenlyfdi'vided sale came employed inure instrument constructedaccording i this invention;

- The, invention 'wnimwbe described with reference to the accompanyingdraWing'sL- Figure" I shows "in "Vertical longitudinal section ananei'nometer constructedi according to this nvention,"'and 'Flgx'2 Isavertical section taken ght angles to the plane of-section of 'Fig'. 11'Fig/3 1's aninverted plan VlGW' -witli-thebase and diaphragmrremoved.Fig. 4 shows in perspective the diaphragm detached from the apparatusand in the position it assumes when subjected to pressure, while themeans by which the diaphragm is connected so as to operate theindicating finger is also shown. Fig. is a plan view of the apparatusdrawn to a smaller scale than the previous figures showing the dial.Fig. 6 shows in partial vertical section an example of construction of atube for receiving the wind pressure. Fig. 7 indicates a portion of aflying machine show ing a position in which the apparatus according tothis invention may be placed.

Referring more particularly to Figs. 1 and 2, the elastic diaphragm 1,which may be composed of india rubber or other elastic material, isfirmly cemented or clamped at its edges preferably being first slightlystretched, between two rings 2, which latter are located between theflanged edges of a circular box-like base 3 and the lower edge of aring}, the two members 3 and 4 being, in the construction shown, heldtogether by the clamping ring 5, and the parts 2,

. 3, 4 and 5 may be composed of metal.

Extending diametrically across the interior of the ring 4 is a frame 6,the ends 7 of which, as indicated at Fig. 3, enter re cesses formed inthe ring 4, and the frame 6 is fitted with a top cover 8 and is formedwith a lower cross bar 9, Figs. 1 and 3. The frame supports the pivotsof a vertical roller 10, Fig. 1, the said pivots having bearingsrespectively in the cross bar 9 and in the cover 8 of the frame 6, andthe upper pivot extends through a dial 11 supported by an annular flangeon the ring 4, and above the dial 11 the pivot of the roller 10 carriesan indicating finger 12, see also Figs. 2 and 5. The indicating finger12 is balanced, as by the extension 12*, and it is particularlyimportant that it should be co-rrectly balanced when the anemometer isintended for use in an aeroplane flying machine; when so used and whenthe indicatingfinger is correctly balanced, the instrument ispractically unaffected by gravity.

The importance of this quality in instruments for this purpose is verygreat, since they are fitted with a view to warning the pilot of loss offlying velocity, and instruments dependent solely on gravity for theircontrol are aflected by the partial falling of the aeroplane consequenton loss of flying speed in such a manner that their readings remain onthe whole unaffected, and so fail to discharge their function, whileinstruments partly controlled by gravity are in like manner partiallyaffected.

The dial 11 is evenly or approximately evenly graduated through nearlythe complete circlunference as shown at Fig. 5, but it will beunderstood that the dial might be graduated to allow for the finger 12making more than a complete revolution.

The vertical roller 10 passes through and is connected to one end of avolute spring 13, Figs. 1 and 2, the opposite end of the spring beingconnected to a stud on the frame cover 8, so arranged that the springnormally carries the indicating finger 12 to its zero position. It isconvenient to adjust the volutespring to a slight initial tension.

Carried by pivots supported in the frame 6, is a horizontal roller 14having its periphery adjacent to the periphery of the vertical roller10, and a cord 15 is attached at one end approximately at the center ofthe elastic diaphragm 1, and extends vertically upward, adjacent to theperiphery of the vertical roller 10, and passes around the horizontalroller 14 and then around the vertical roller 10, to which the other endof the cord 15 is fixed. The upper part of the case composed by the ring4 is covered w th a transparent air-tight cover 16.

The general arrangement of the rollers 10 and 14 can be very readilyunderstood by the perspective view at Fig. 4 which also indicates thevolute spring 13, the diaphragm in this case being shown depressed, thatis in the position it assumes when subjected to air pressure.

It has already been stated that one side of the diaphragm is acted uponby the pressure transmitted through the tube to the closed chamber, andin the construction described with reference to the drawings, theopposite side of the diaphragm forms a wall of the circular box-likebase 3. At Fig. 6 of the drawings is shown a double tube of the combinedPitot and static pressure type, the inner tube 17- of which is held in aposition to recei e the air pressure, and is connected with the closedchamber 20 formed in the casing of the apparatus between the transparentcover 16 and the diaphragm 1, while the outer tube 21 is connected withthe chamber below the diaphragm.

Referring to Fig. 6 the central tube 17 is held in a position to receivethe air pressure entering in the direction indicated by the arrow, andwhich may be termed the forward end of the tube, and the rear end of thetube 17 is connected by a flexible or other pipe 18, Fig. 7, with anozzle 19 opening into the chamber 20.

The tube 17, Fig. 6, is surrounded by the outer tube 21, there being anannular space between the exterior of the tube 17 and the interior ofthe tube 21, which annular space is closed at its ends by rings 22.Apertures 23, Fig. 6, are formed through the wall of the outer tube 21at adistance from the forward end thereof, and a nozzle 24 is provided,communicating with the annular space within the tube 21, so that whilepressure passes into the tube 17 and so to the chamber 20 of theapparatus, atmospheric pressure is maintained on the opposite side ofthe diaphragm by the nozzle 24, Fig. 6,

being connected by a flexible or other tube, such as 25 Fig. 7, with anozzle 26, Fig. 2, communicating with the chamber 27 formed by thebox-like base 3 and the elastic diaphragm 1.

VVhen the anemometer is applied, as in the example shown at Fig. 7, to aflying machine, the tube 17 Fig. 6, is supported in a position with itsopen end facing the direction of travel of the machine, and theinstrument described with reference to Figs. 1 to 6 is arranged, asindicated at 28 Fig. 7, so that the dial can readily be observed by thepilot. When the machine is in motion, pressure will be conveyed to thechamber 20, igs. 1 and 2, of the apparatus, while simultaneously thechamber 27 beneath the elastic diaphragm 1 may be maintained atatmospheric pressure, and thus the diaphragm will be extended in adownward direction, and the indicating finger 12 will be moved. Theelastic diaphragm 1 o-ifers greater resistance to movement in proportionas it becomes expanded or inflated, and therefore the indicating finger12 is moved over the evenly Fig. 5.

Where the apparatus is employed for measuring wind speed at a fixedstation, the ingraduated scale, as indicated at strument canconveniently be connected to any well known type of swiveling wind tube.

What I claim as my inventionand desire to secure by Letters Patent is 1.An anemometer or air speed indicator comprising in comb1nat1on: abox-like case,

a transparent plate hermetically closing one 1 end of said case, "anelastic diaphragm adapted to dilate under pressure arranged parallelwith said plate and dividing said case into two compartments, a tubecorn-- municating at one end with one compartment and open at its otherend toreceive the flow of air the speed of which is to be measured,means to maintain the other compartment at atmospheric pressure, anapproximately evenly divided dial, a spindle rotatably mounted withinsaid case, an indicating finger on'said spindle, a positive connectionbetween said spindle and diaphragm adapted to communicate angularmovement to said finger with respect to said dial in'a regularprogression proportionate to the movement of the diaphragm when saiddiaphragm is distended by air pressure due to its velocity, and means toreturn said finger toward its original position on said dial as thepressure on said diaphragm becomes reduced. i I

2. An anemometer or air speed indicator comprising in combination: abox-like case, a transparent plate hermetically closing one end of saidcase, an elastic diaphragm adapted to dilate under pressure arrangedparallel with said plate and dividing said case into two compartments,an open-ended tube communicating at one end throughia passage in saidcase with the interiorof one compartment the other end of'the tubebeing.

arranged to receive the flow ofairthe' speed of which is to be measured,a 's'econdjtube communicating at one end through a passage in said casewith the, interior of the other compartment, the other end of said tubecommunicating with the atmosphere and located in such a position thatthe pressure of the air within said tube and therefore in saidcompartment is uninfluenced by any relative movement of air surroundingsaid tube, an approximately evenly divided dial,

a spindle rotatably mounted within said case, an indicating finger onsaid spindle, a positive connection between said spindle and diaphragmadapted to communicate angular movement to said finger with respect tosaid dial in a regular progression proportionate to the, movement of thediaphragm when said diaphragm is distended by air under pressure due toits velocity, and means vadaptedto return said finger toward its beinglocated to receive air under pressure in accordance with the speed ofits flow, an approx mately evenly divided dial in sald compartment, aframe extendmg across said compartment, a spindle rotatably carried bysaid frame, a balanced indicating finger on said spindle, a positiveconnection between said spindle and diaphragm adapted to communicateangular movement to said.

finger with respect to said dial in a regular progression proportionateto the movement of the diaphragm when said diaphragm is distended, meansto maintain the other compartment at atmospheric pressure and a springfixed at one end to said spindle and at the other end to said frame togradually return said finger to its original position on "said dial asthe pressure on said diaphragm becomes reduced.

4:. An anemometer or air speed indicator comprlslng in comb1nat1on: anopen-ended box-like case, a transparent plate hermetically closing'oneend of said case, an elastic diaphragm adapted to dilate under pressureand to close the other end of said case, means for fixing said diaphragmto said case, a tube to communicate at one end with the interior of saidcase and open at its other "end receive the'fiow' of air "speed 7 ofwhich is'j'tobe--measured,.' an approxi 1'mately',-evenlydivided dial, aspindle rotasaid spindle, a positive connection between phragm when thediaphragm is distended by pressure. of air in said case, means to Ireturn said finger toward its original position as the pressure on saiddiaphragm be comes reduced, an open box-like base, means for fixing andclamping the edges of said base to the edges'of said diaphragm to form achamber at the rear of said diaphragm,

l and an open-ended tube one end of which communicates with said chamberthe other end of said tube being so arranged as to preserve a staticpressure within said chamber.

5. An anemometer or air speed indicator comprising in combination: aox-like case,

a transparent plate hermetical y closing one end of said case, anelastic diaphragm adapted to dilate under pressure arranged parallelwith said plate and dividing said case into two compartments, anopen-ended tube communicating at one end with the compartment of saidcase between said plate and diaphragm the other end of said tube beingarranged to receive the flow of air the speed of which is to bemeasured, an approximately evenly divided dial in said compartment, aframe extending across said compartment, a spindle rotatably carried bysaid frame, an indicating finger on said spindle, a roller surroundingand fixed to said spindle, a second roller carried by said framerevoluble about an axis at right angles to said spindle, a cordconnected at one end at about the center of said diaphragm and extendingaround said second and first rollers and having its opposite end fixedto said first roller so that when said diaphragm is distended saidfinger is caused to move around said dial to an extent corresponding tothe dilation of the diaphragm, a spring ma ame I fixed at oneend to saidspindle and at the other end to said frame to return said fingertoward'its original position on said dial as pressure on said diaphragmbecomes reduced, a tube communicating at one end with the interior ofsaid compartment its other end being located to receive the flow of airthe speed of which is to be measured, and an open-ended tube one end ofwhich communicates with the interior of the other compartment of saidcase the other end of tably mounted within said case, an indicatingfingeron said spindle, a positive connection between said spindle anddiaphragm adapted to communicate angular movement to said finger withrespect to said dial in regular progression proportionate. to themovement of. the diaphragm due to the variation of pressure in one ofsaid compartments, a double tube of the combined Pitot and staticpressure tube type located in a position to receive the flow of air, thespeed of which is to be measured, a tube connecting the delivery end ofthe inner tube of said Pitot and static pressure tubes with the interiorof the compartment between the. diaphragm and said transparent plate toconvey said pressure to said compartment, and a tube connecting theouter static pressure tube to the other compartment substantially as setforth.

In witness whereof I have hereunto set my hand in the presence of twowitnesses.

ALP-1C OGILVIE.

Witnesses GRIFFITH BREWER, WILLIAM A. MARSHALL.

